In the development of apparatuses and methods for detection and/or analysis of volatile compounds contained in a sample or milieu, improvements of all components and steps are of interest.
In our PCT application WO 98/57141 is disclosed a system for the detection of an analyte in air. The collected air sample is transported to a first enrichment stage for enrichment of the analyte comprising a thermally regulated adsorption/desorption filter creating a non-laminar gas flow for adsorption of the analyte on the filter surfaces, encased in a housing having a gas inlet and a gas outlet connected to valves. The desorbed analyte from the filter is transported to a second enrichment stage, comprising a cold trap, for the further enrichment of the gaseous analyte by condensing the analyte, followed by extraction of the condensed material with a solvent, and collection of the solution enriched in analyte from the cold trap for transport to an analysis unit.
By transporting the desorbed analyte out of the filter housing with a weak gas flow to a cold trap for condensing the analyte on its walls and then rinsing the cold trap with a liquid to obtain a small liquid sample, some of the analyte is lost. It would be desirable to greatly reduce or eliminate the loss of analyte, i.e. loss of condensed volatile compounds, encountered in the prior art, particularly in cases where very small amounts of volatile compounds, in nanogram or picogram region, are to be detected or analyzed.